Traditionally the emphasis at each annual Denver X-ray Con­ ference is placed on a particular aspect of X-ray analysis. The past decade has seen a steady expansion of applications of port­ able X-ray analyzers and probes in the field, in boreholes and in plant process streams. With this in mind, the main theme of the current conference is field applications of X-ray fluorescence with particular reference to analysis of raw materials such as rocks, ores and coal. The Plenary Session took up this theme with two invited papers reviewing applications of X-ray emission techniques to geochemical, borehole and on-stream analysis, and recent developments in port­ able instruments for alloy, ore and other analyses. The third paper took us further afield with a review of X-ray spectrochemical analy­ sis on Mars, the Moon and Earth. It is evident that portable X-ray analyzers are finding more and more applications outside the conventional boundaries of X-ray spectrometry. Users are not analysts and sometimes not even scien­ tists. Until recently this trend has been hindered by the "scien­ tific nature" of the instruments; one needs to understand XRF meth­ ods in order to properly operate the instrument. Microprocessor technology has made possible the development of precalibrated, "smart" analyzers with readouts in quantities familiar to the user and interlocks to prevent erroneous operation. Further developments along these lines were reported at this conference.